Biomedical subjects

Bing Chen

Publications and source records attributed to Bing Chen.

At least 73 records · Page 4Linked to original sources

PubMed2004

SU5416 is a potent inhibitor of hepatocyte growth factor receptor (c-Met) and blocks HGF-induced invasiveness of human HepG2 hepatoma cells.

BACKGROUND/AIMS: SU5416 is a potent inhibitor of receptor tyrosine kinases, including those of the vascular endothelial growth factor receptor, stem cell factor receptor, and platelet-derived growth factor receptor. Because of the overwhelming evidence favoring the role of aberrant hepatocyte growth factor (HGF)/Met signaling in the pathogenesis of various human cancers, various inhibitor strategies have been employed to therapeutically target this receptor. METHODS: Cell proliferation was determined by incorporation of [(3)H] thymidine. Invasiveness was assayed in Boyden Chambers with 8 microm Matrigel coated filters. Phosphorylation of ERK1/2, Akt by HGF stimulation was detected by Western blotting. RESULTS: We found that SU5416 inhibited motility scattering and the invasive activity of a hepatocellular carcinoma cell line HepG2 in vitro and growth in primary cultured hepatocytes induced by HGF. Consequently, tyrosine autophosphorylation of the c-met induced by HGF was inhibited in these cells by SU5416 in a dose-dependent manner. Furthermore, ERK1/2 and Akt phosphorylation, the signaling events down-stream of c-met activation were reduced. Moreover, SU5416 caused reversion in NIH3T3 fibroblasts transformed by the oncogenic form of the receptor, Tpr-Met. CONCLUSIONS: Inhibition of various solid tumors growth and metastasis by SU5416 may be partially attributed to blocking activation of the hepatocyte growth factor receptor.

3T3 Cells↗

PubMed2004

PeLM: modeling of pesticide-losses through runoff and sediment transport.

A GIS-aided pesticide loss model (PeLM) was developed to simulate pesticide losses through surface runoff and sediment transport in watershed systems. The PeLM could tackle the movement of eroded soil along with surface runoff as well as the pesticide losses in adsorbed and dissolved phases. The contributions of different soil types in the sediment were also examined. The model was applied to the Kintore Creek Watershed of southern Ontario, Canada. The simulation results were verified through observed data, indicating a correlation level of 0.89-0.98. The results also showed that clay particles usually held the largest share of contributions to pesticide losses through soil erosion. This study is significant in the efforts for modeling nonpoint source pollution in watershed systems. It provides useful information and support for the related decisions of watershed management.

Geographic Information Systems↗

PubMed2004

A chimeric protein of simian immunodeficiency virus envelope glycoprotein gp140 and Escherichia coli aspartate transcarbamoylase.

The envelope glycoproteins of the human immunodeficiency virus and the related simian immunodeficiency virus (SIV) mediate viral entry into host cells by fusing viral and target cell membranes. We have reported expression, purification, and characterization of gp140 (also called gp160e), the soluble, trimeric ectodomain of the SIV envelope glycoprotein, gp160 (B. Chen et al., J. Biol. Chem. 275:34946-34953, 2000). We have now expressed and purified chimeric proteins of SIV gp140 and its variants with the catalytic subunit (C) of Escherichia coli aspartate transcarbamoylase (ATCase). The fusion proteins (SIV gp140-ATC) bind viral receptor CD4 and a number of monoclonal antibodies specific for SIV gp140. The chimeric molecule also has ATCase activity, which requires trimerization of the ATCase C chains. Thus, the fusion protein is trimeric. When ATCase regulatory subunit dimers (R(2)) are added, the fusion protein assembles into dimers of trimers as expected from the structure of C(6)R(6) ATCase. Negative-stain electron microscopy reveals spikey features of both SIV gp140 and SIV gp140-ATC. The production of the fusion proteins may enhance the possibilities for structure determination of the envelope glycoprotein either by electron cryomicroscopy or X-ray crystallography.

Amino Acid Sequence↗

PubMed2004

[Evaluation of safety on the noise of drills in the tympanoplasty].

OBJECTIVE: To investigate the effect of noise generated by the otologic drills and suctions on the cochlear of the operated and nonoperated ear. METHOD: To examine the noise generated by the different kind of drills and suctions in tympanoplasty, the ND10 Sound Level Meter (Beijing) was used. The bone-conduction thresholds was measured before and one month after operation respectively in both ears. RESULTS: Sound pressure levels for the otologic drills and suctions were 82-106 dB and 71-84 dB, respectively. There was no statistically significant difference between pre-noise and one-month post-noise bone-conduction thresholds in both operated and nonoperated ears. CONCLUSION: It is safety to use otologic drills and suctions for the patients. There is no apparent harmful effect on the function of cochlear in both ears for the noise of using drills and suctions in tympanoplasty.

Evaluation Studies as Topic↗

PubMed2004

[Cloning and expression of human interleukin-21 cDNA in E.coli].

AIM: To clone full length cDNA of human interleukin-21 (IL-21) and express it in E.coli. METHODS: Total RNA was isolated from peripheral lymphocyte stimulated with anti-CD3 antibody. 5' and 3' terminal fragments of IL-21 gene (242 bp and 425 bp fragments respectively) were amplified using RT-PCR. The full length IL-21 cDNA was amplified by recombination PCR from the products of RT-PCR. The expression plasmid pET28a(+)-IL21 was constructed by inserting IL-21 cDNA into pET28a(+)and then was transformed into BL21(DE3). Expression of hIL-21 was induced by IPTG at 37 degrees Celsius for 5 h. The target protein was purified through Ni(2+)-chelating Sepharose Fast Flow. Purified rhIL-21 was refolded by using dialysis method. And the bioactivity was detected by MTT on costimulating the T cell proliferation with anti-CD3. RESULTS: IL-21 was cloned and expressed in E.coli successfully. SDS-PAGE analysis showed the IL-21 was expressed in the form of insoluble inclusion body. The refolded rhIL-21 could stimulate the proliferation of mature human T-cells in the presence of anti-CD3. CONCLUSION: The rhIL-21 with bioactivity was obtained, which lays the foundation for study of its function.

Antibodies, Monoclonal↗

PubMed2004

[Survey of alkylphenols in aquatic environment of Zhujiang Delta].

The summer contamination of dissolved nonylphenols (NPs) and octylphenol (OP) in surface water of Zhujiang estuary and other rivers of Zhujiang Delta was analyzed. The result reveals that NPs concentration in The Pearl River remains < 20-40 ng/L, apart from the NPs concentrations of the mouth of The Pingzhou Channel the mouth of The Shawan Channel and Hutiaomen reaching a higher level of 98.84, 129.82 and 164.98 ng/L respectively. The Lingding Sea and open sea surface water keep at a lower level with the NPs concentration of < 10-14 ng/L. In terms of OP concentration in The Pearl River, any other sampling location is below LOD 2 ng/L, except for Baiertan, the mouth of The Shawan Channel and Hutiaomen being 2.89, 2.44, 2.12 ng/L respectively and inside Macao harbor being the highest level of 8.54 ng/L. The OP concentrations of The Lingding Sea and open sea surface water are lower than LOD 1 ng/L.

China↗

PubMed2004

[Regeneration of autologous tissue-engineered cartilage by using basic-fibroblast growth factor in vitro culture].

OBJECTIVE: To investigate the effect of the basic fibroblast growth factor (b-FGF) to regenerate an autologous tissue-engineered cartilage in vitro. METHODS: The Cells were harvested from the elastic auricular cartilage of swine,and were plated at the concentration of 1 x 10(4) cells/cm2 , studied in vitro at two different media enviroments: Group I contained Ham's F-12 with supplements and b-FGF, Group II contained Ham's F-12 only with supplements. The passage 2 cells (after 12.75 +/- 1.26 days) were harvested and mixed with 30% pluronic F-127/Ham's F-12 at the concentration of 50 x 10(6) cells/ml. It was injected subcutaneously at 0.5 ml per implant. The implants were harvested 8 weeks after the vivo culture and examined with the histological stains. RESULTS: The chondrocytes displayed morphologically similar to the fibroblasts in the media containing basic-FGF. The number of cell doublings (after 12.75 +/- 1.26 days) in vitro culture was as the following: Group I, 70; Group II, 5.4. Eight 8 weeks after the vivo autologous implantation, the average weight (g) and volume (cm3) in each group was as the following: Group I, 0.371 g/0.370 cm3 Group II, 0.179 g/0.173 cm3 (P < 0.01). With the b-FGF in vitro culture, the cells were expanded by 70 times after 2 weeks. Histologically, all of the engineered cartilage in the two groups were similar to the native elastic cartilage. CONCLUSION: These results indicate that the basic-FGF could be used positively to enhance the quality and quantity of the seeding cells for the generation of the well-engineered cartilage.

Animals↗

PubMed2004

[Study on cryopreservative methods for dendritic cells derived from K562 cell line].

To investigate the biological properties of cryopreserved dendritic cell (DC) derived from K562 cell line, thus to provide a simple, quick and efficient preservative method of DC for infusion of DC to patients with leukemia after complete remission, fresh DC induced from K562 cell line (K562-DC) was frozen in -196 degrees C liquid nitrogen and -80 degrees C mechanical freezer by method of steps (RPMI 1640 with 10% DMSO, 20% FCS as cryopreservatives), and thawed in different time, respectively. Survivals of cryopreserved and fresh K562-DC, expression of surface antigens, stimulating index (SI) and cytotoxic eliminating rate were detected. The results of fresh induced cells were compared with that of cryopreserved ones. The results showed that before and after frozen in liquid nitrogen, the morphological characteristics of K562-DC had no distinct change; and both their expression rates of surface molecular and capacity to stimulate allogeneic lymphocyte had no statistic significance (P > 0.05). In addition, there were no differences in terms of viability, stimulatory capacity and cytotoxicity of K562-DC from two ways for less than one month (P > 0.05), but there were differences when frozen for more than one month (P < 0.05). It is concluded that there is no significant difference when frozen less than one month between liquid nitrogen and -80 degrees C freezer; but when time is more than one month, K562-DC frozen in -196 degrees C liquid nitrogen is better than that in -80 degrees C freezer.

Antigens, Surface↗

PubMed2004

[Simultaneous determination of amino acids in food by capillary electrophoresis with indirect ultraviolet detection].

The characteristic of capillary electrophoresis (CE) with indirect ultraviolet (UV) detection of L-ornithine (Orn), L-proline (Pro) and L-glutamine (Gln) was investigated. A suitable electrolyte consists of 5 mmol/L sodium p-aminobenzene sulfonic acid-10 mmol/L KH2PO4 (pH 11.5) with UV detection at 254 nm. The applied voltage was set at 12 kV. The three amino acids were completely separated and detected by the method in 11 min. The relative standard deviations (RSD) of the method were better than 0.72% for migration time and 2.0% for peak height. The detection limits of Orn, Pro and Gln were 6.78, 8.71 and 7.86 mg/L, respectively. The proposed method was successfully applied to the determination of amino acids in foods (Haitian soybean sauce, Tsingtao beer and amino acids tonic) and the recoveries were in the range of 96.8% - 104%.

Amino Acids↗

PubMed2003

The primary mechanism of attenuation of bacillus Calmette-Guerin is a loss of secreted lytic function required for invasion of lung interstitial tissue.

Tuberculosis remains a leading cause of death worldwide, despite the availability of effective chemotherapy and a vaccine. Bacillus Calmette-Guérin (BCG), the tuberculosis vaccine, is an attenuated mutant of Mycobacterium bovis that was isolated after serial subcultures, yet the functional basis for this attenuation has never been elucidated. A single region (RD1), which is absent in all BCG substrains, was deleted from virulent M. bovis and Mycobacterium tuberculosis strains, and the resulting DeltaRD1 mutants were significantly attenuated for virulence in both immunocompromised and immunocompetent mice. The M. tuberculosis DeltaRD1 mutants were also shown to protect mice against aerosol challenge, in a similar manner to BCG. Interestingly, the DeltaRD1 mutants failed to cause cytolysis of pneumocytes, a phenotype that had been previously used to distinguish virulent M. tuberculosis from BCG. A specific transposon mutation, which disrupts the Rv3874 Rv3875 (cfp-10 esat-6) operon of RD1, also caused loss of the cytolytic phenotype in both pneumocytes and macrophages. This mutation resulted in the attenuation of virulence in mice, as the result of reduced tissue invasiveness. Moreover, specific deletion of each transcriptional unit of RD1 revealed that three independent transcriptional units are required for virulence, two of which are involved in the secretion of ESAT-6 (6-kDa early secretory antigenic target). We conclude that the primary attenuating mechanism of bacillus Calmette-Guérin is the loss of cytolytic activity mediated by secreted ESAT-6, which results in reduced tissue invasiveness.

Animals↗

PubMed2003

Alphavbeta6-Fyn signaling promotes oral cancer progression.

We have previously shown that the integrin beta6 is neo-expressed in invasive oral squamous cell carcinoma (SCC) and is correlated with oral tumor progression. However, the mechanism by which the integrin beta6 promotes oral tumor progression is not well understood. The purpose of the present study was to determine whether integrin beta6 signaling activates Fyn and thus promotes oral squamous cell carcinoma progression. We analyzed the integrin beta6 signaling complex and investigated the function of these signaling molecules in oral SCC cells. We found that, upon ligation of the integrin beta6 with fibronectin, beta6 complexed with Fyn and activated it. The activation of Fyn recruited and activated focal adhesion kinase to this complex. This complex was necessary to activate Shc and to couple beta6 signaling to the Raf-ERK/MAPK pathway. This pathway transcriptionally activated the matrix metalloproteinase-3 gene and promoted oral SCC cell proliferation and experimental metastasis in vivo. These findings indicate that integrin beta6 signaling activates Fyn and thus promotes oral cancer progression.

Animals↗

PubMed2003

[Relationship of atherogenesis and proteoglycans in wall of vein graft, an experimental study].

OBJECTIVE: To investigate the relationship between the concentrations of proteoglycans (PGs) and progress of atherogenesis in grafted vein. METHODS: A section of common carotid artery with a length of 0.5 cm was cut off and then a section of vein was implanted to the damage among 72 male New Zealand rabbits. Then the rabbits were randomly divided into two groups of 36 rabbits to be fed with high fat diet and ordinary diet respectively. Every six rabbits were killed one week, 2 weeks, 4 weeks, 8 weeks, 12 weeks, and 20 weeks after the operation. The implanted veins were taken to be observed by electron microscopy. The PGs in the implanted veins were extracted and divided into heparan sulfate proteoglycan (HSPG), chondroitin sulfate proteoglycan (CSPG), and dermatan sulfate proteoglycan (DSPG) by anion-exchange chromatography 8, 12, and 20 weeks postoperatively. The concentrations of PGs were measured. Blood was extracted from the heart to examine the level of LDL-cholesterol. The normal jugular veins on the opposite side were used as controls. RESULTS: The level of LDL-cholesterol in the high fat diet group was 26.5 +/- 7.49 mmol/L, significantly higher than that in the normal diet group (0.71 +/- 0.65 mmol/L, P < 0.05). In the normal diet group, the content of CSPG-DSPG was 1,077 +/- 116 micro g/g, significantly higher than that of the normal vein (809 +/- 75 micro g/g, P < 0.05), and not significantly different from that of the normal diet group (1,077 +/- 116 micro g/g) 8 weeks postoperatively, and became lower 12 and 20 weeks postoperatively (773 +/- 49 and 819 +/- 45 micro g/g respectively), both similar to that of normal vein (both P > 0.05). Foam cells were found 20 weeks postoperatively. In the high fat diet group, the content of CSPG-DSPG was 1,089 +/- 94 micro g/g 8 weeks postoperatively, significantly higher than that of normal vein (P < 0.05), and the high level lasted till the 20 th postoperative week (1,068 +/- 100 micro g/g, P < 0.05). Foam cells were detected as early since the 4 th postoperative week, unorganized areas were found 20 weeks after the operation. The HSPG content was not significantly different among the high fat diet group, normal diet group, and the normal vein (with a range of 213 +/- 34 - 278 +/- 33 micro g/g), The proportion of HSPG in total PGs 8, 12, and 20 weeks postoperatively in the high fat diet group were 19.6%, 18.6%, and 16.6% respectively, lower than those in the normal diet group (18.8%, 21.9%, 21.9%) and much lower than that in the normal vein (25.55%). CONCLUSION: CSPG-DSPG has auxo-action on atherogenesis in graft, but HSPG protects the graft against atherogenesis to an extent.

Animals↗

PubMed2003

Pesticide runoff model (PeRM): a case study for the Kintore Creek Watershed, Ontario, Canada.

An integrated model, the Pesticide Runoff Model (PeRM), has been developed to predict pesticide losses due to runoff by considering the emission, degradation, adsorption and desorption of pesticides, as well as their movement in dissolved and adsorbed phases. The developed modeling system has been used to calculate the losses of atrazine from agricultural lands in the Kintore Creek Watershed, Ontario, Canada between 1988 and 1992. The modeling outputs have been verified against actual monitoring data, which were obtained from a water quality monitoring project carried out in the same watershed over the same period of time.

Agriculture↗

PubMed2003

Vaccine efficacy of a lysine auxotroph of Mycobacterium tuberculosis.

The in vivo growth phenotype and vaccine efficacy of a lysine auxotrophic mutant of Mycobacterium tuberculosis strain H37Rv are described. An immunization experiment using a mouse model with an aerosol challenge showed that two doses of the M. tuberculosis mutant were required to generate protection equivalent to that of the Mycobacterium bovis BCG vaccine.

Animals↗

PubMed2003

Radiation enhances the anti-tumor effects of vaccinia-p53 gene therapy in glioma.

The overall goal of this study was to analyze the effect and mechanism of radiation in combination with vaccinia viruses (VV) carrying the p53 gene against glioma. Comparison of two alternative treatments of cultured C6 (p53(+)) and 9L (p53(-)) rat glioma cells showed significantly reduced survival for both cell lines, especially 9L, when radiation was applied prior to virus versus radiation alone. High p53 protein expression mediated by VV-TK-p53 was measured in infected cells. Single modality treatment of C6 cells with psoralen and UV (PUV)-inactivated VV-TK-p53 (PUV-VV-TK-53) or radiation significantly decreased survival compared with PUV-inactivated L-15 (PUV-L-15) control virus. However, no difference was observed between radiation and combination treatments of C6 cells. In contrast, radiation followed by PUV-VV-TK-53 resulted in dramatic reduction of 9L cell viability, compared to single modality treatment. Flow cytometry analysis of Annexin-V-stained 9L cells showed that radiation and PUV-VV-TK-53 caused a significant decrease in live cells (17.2%) as compared to other treatments and control (61.6-98.3%). Apoptosis was observed in 37.2% of cells, while the range was 0.7-7.8% in other treatment groups; maximal p53 level was measured on day 7 post-infection. In athymic mice bearing C6 tumors, VV-TK-53 plus radiation in both single and multiple therapies resulted in significantly smaller tumors by day 30 compared to the agents given only once. Immunohistochemical analysis of tumor sections demonstrated p53 protein expression over 20 days after VV-TK-53 treatment. Analysis of blood and spleen cells of mice given multiple combination treatments showed significant splenomegaly, leukocytosis, and increased DNA synthesis and response to mitogen. Multiple combination treatments were also associated with significantly elevated natural killer and B cells in the spleen. There were no overt toxicities, although depression in red blood cell and thrombocyte parameters was noted. Collectively, the data demonstrate that radiation significantly improves the efficacy of VV-mediated tumor suppressor p53 therapy and may be a promising strategy for glioma treatment. Furthermore, the results support the conclusion that the mechanisms underlying the enhanced anti-tumor effect of combination treatment include apoptosis/necrosis and upregulation of innate immune defenses.

Animals↗

PubMed2003

Influence of CYP2D6*10B genotype on pharmacokinetics of propafenone enantiomers in Chinese subjects.

AIM: To study the relationship between genotype of CYP2D6*10B and pharmacokinetics of propafenone enantiomers. METHODS: Genotype of 17 healthy Chinese HAN subjects was determined by an allele specific amplification method. The blood samples (0-15 h) of the subjects were taken after oral administration of a single dose (400 mg) of propafenone hydrochloride. Concentrations of propafenone enantiomers in plasma were measured by a reverse-phase HPLC with precolumn derivatization. RESULTS: Seventeen subjects characterized for CYP2D6*10B genotype included (*1/*1) (n=4), (*1/*10) (n=5) and (*10/*10) (n=8). The metabolic ratios (lg MR) of the three genotypes were -2.68+/-0.23, -2.2+/-0.7, and -1.1+/-0.5, respectively. The AUC of the three groups were (1534+/-334), (1891+/-793), (3171+/-1075) microg.h.L(-1) for S-enantiomer and (1136+/-345), (1467+/-817), (2277+/-745) microg.h.L(-1) for R-enantiomer, respectively. The AUC of propafenone enantiomers in *10/*10 is about 1.5-2 times of that of *1/*10 group or *1/*1 group, and the CL of both enantiomers in *10/*10 is only half of that of *1/*10 group or *1/*1 group (P<0.05). CONCLUSION: CYP2D6*10B alleles induce the declined activity of CYP2D6 and impair the metabolism of propafenone.

Adult↗

PubMed2003

[Research of relationship between endoneurial fluid pressure and electroneurography of the facial nerve].

OBJECTIVE: The relationship between endoneurial fluid pressure (EFP) and electroneurography (ENoG) of the facial nerve was studied in order to evaluate the ENoG as the basis of pathophysiology of the decompression of the facial nerve. METHODS: The values of ENoG were recorded by an instrument of physiology on the normal and crushed facial nerves of guinea pigs. Endoneurial fluid pressures were measured by a servo-nulling micropipette system at the same time. After the EFP were measured, the facial nerves were removed and fixed properly for examination under the light and electron microscope in order to determine the differences from various periods after injury. RESULTS: EFP in the facial nerve was changed significantly during the period of three days to three weeks later after crushed injury, and the percentage of degenerated facial nerve fibre was the same. There was positive correlation between ENoG and EFP. After crushed injury 2 and 3 weeks, the coefficient was 0.88 and 0.51, respectively. It could be found that extensive edema in endoneurial and perivascular spaces of the facial nerve occurred in early stage of injury, but numerous Schwann cells proliferation appeared in the later period. CONCLUSION: The change of ENoG could reflect the value of EFP relatively within three weeks after crushed injury. It was suggested that ENoG could be useful in evaluating the pathogenesis underlying facial palsy. And it could be provided a basis indication for decompression of the facial nerve.

Animals↗

PubMed2003

[Construction and expression of retroviral vector containing bone morphogenetic protein-7].

AIM: To achieve stable and long-term expression of BMP-7 gene in bone marrow stem cells (BMSCs). METHODS: Retrovirus expression vector containing BMP-7 gene was constructed and transfected into packaging cells PT67. After puromycin selection and cells cloning, cell clones producing high level of recombinant virus were obtained. The viruses were used to infect directly BMSCs and the expression of BMP-7 gene in BMSCs was analyzed by immunohistochemical staining. RESULTS: Retrovirus vector containing BMP-7 gene was successfully reconstructed and BMP-7 was expressed in the BMSCs.The transfection rates was about 30%-40%. CONCLUSION: The construction of recombinant retrovirus vector containing BMP-7 gene can provide a reliable tool for the formation of bone or cartilage seed cells in the research of tissue engineering.

Bone Marrow Cells↗